Electric circuit body and air conditioner

Abstract

To provide an electric circuit body and the like of high reliability.SOLUTION: An electric circuit body 100 includes: a noise filter circuit 10 connected to a 3-phase 4-line-type AC power source E1; an inverter circuit 20 connected to an output side of the noise filter circuit 10 via three phase power lines 8R, 8S, 8T different from a neutral line 8N; and a power source circuit 30 to which single-phase AC voltage is applied via one of the three-phase power lines 8R, 8S, 8T and the neutral line 8N. The noise filter circuit 10 has at least three first varistors 1R, 1S, 1T, each of the first varistors 1R, 1S, 1T is individually connected to the three-phase power lines 8R, 8S, 8T at one end, and the other ends are not connected to the neutral line 8N.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to electrical circuits and the like. [Background technology]

[0002] Regarding an electric circuit body to which power is supplied from a three-phase, four-wire AC power source, for example, the technology described in Patent Document 1 is known. That is, Patent Document 1 describes a power conversion device that includes "a power conversion module that converts output power from three phases excluding the N phase of a three-phase, four-wire power source consisting of the R phase, the S phase, the T phase, and the N phase" and also includes "an N-phase loss detection unit that detects loss of the N phase using a drive control power source as a power source." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-169334 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, a surge protection element such as a varistor may be provided on a three-phase power line to protect a circuit from transient abnormal voltages such as external disturbance surges and lightning surges. If the technology of Patent Document 1 is applied to such a configuration, an overvoltage (line voltage) is applied to the surge protection element when an N-phase (neutral line) is lost, which may damage the surge protection element.

[0005] Therefore, an object of the present disclosure is to provide an electric circuit body or the like with high reliability. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the electric circuit body according to the present disclosure includes a noise filter circuit connected to a three-phase four-wire AC power supply, an inverter circuit connected to the output side of the noise filter circuit via three-phase power lines different from a neutral line, and a power supply circuit to which a single-phase AC voltage is applied via one of the three-phase power lines and the neutral line, and the noise filter circuit has at least three first surge protection elements, one end of each of the first surge protection elements being connected to an individual one of the three-phase power lines and the other end not connected to the neutral line. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a highly reliable electric circuit body, etc. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram including an electric circuit body according to a first embodiment. [Diagram 2] FIG. 1 is a circuit diagram showing a configuration of an electric circuit body according to a first embodiment. [Diagram 3] FIG. 11 is a circuit diagram showing a configuration of an electric circuit body according to a second embodiment. [Figure 4] FIG. 11 is a configuration diagram of an air conditioner according to a third embodiment. [Diagram 5] FIG. 11 is a perspective view of a state in which the side panels and top panel have been removed from the housing of the outdoor unit of an air conditioner according to a third embodiment. [Figure 6] FIG. 11 is a circuit diagram showing a configuration of an electric circuit body according to a first modified example. [Figure 7] FIG. 11 is a circuit diagram showing a configuration of an electric circuit body according to a second modified example. [Figure 8] FIG. 11 is a circuit diagram showing a configuration of an electric circuit body according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment FIG. 1 is a circuit diagram including an electric circuit body 100 according to a first embodiment. The electric circuit body 100 shown in Fig. 1 has a function of performing a predetermined power conversion using AC power supplied from a three-phase, four-wire AC power source E1 (see Fig. 2), as well as a function of protecting circuit elements from disturbance surges and lightning surges. As shown in Fig. 1, the electric circuit body 100 includes a terminal block B1, a noise filter board B2, an inverter board B3, and a control board B4. The terminal block B1 is a device used to connect R-phase, S-phase, and T-phase power lines and an N-phase neutral wire of a three-phase, four-wire system.

[0010] The "three-phase four-wire system" refers to a system for distributing three-phase AC power using R-, S-, and T-phase power lines and an N-phase neutral line. The N-phase neutral line is drawn from the neutral point on the secondary side of a star-connected transformer (not shown), for example. By using such a three-phase four-wire power distribution system, two types of power sources, three-phase AC power and single-phase AC power, can be obtained. Therefore, the three-phase four-wire power distribution system is particularly effective when three-phase loads and single-phase loads are mixed. As shown in FIG. 1, the R-, S-, and T-phase power lines and the N-phase neutral line are connected to a noise filter board B2 via a terminal block B1.

[0011] The noise filter board B2 is a board for suppressing disturbance surges and lightning surges. A noise filter circuit 10 (see FIG. 2), which will be described later, is mounted on the noise filter board B2. The noise filter board B2 is connected to an inverter circuit 20 via R-phase, S-phase, and T-phase power lines. In addition, a predetermined single-phase AC power is supplied from the noise filter board B2 to each of a power supply circuit 30, an instantaneous power interruption detection circuit 40, and a 200V load 50 via the R-phase power line and the N-phase neutral line.

[0012] The inverter circuit 20 is a power converter that sequentially rectifies and smoothes three-phase AC power, and further converts the DC power into a predetermined AC power and outputs it to the motor M1. The motor M1 is used, for example, as a drive source for a compressor of an air conditioner. The power supply circuit 30 is a circuit for generating predetermined voltages corresponding to the microcomputer 25 (see FIG. 2) and control circuit 26 (see FIG. 2) of the inverter circuit 20, as well as the microcomputer 44 (see FIG. 2) of the instantaneous power interruption detection circuit 40. As shown in FIG. 1, the inverter circuit 20 and the power supply circuit 30 are mounted on an inverter board B3.

[0013] The momentary power interruption detection circuit 40 is a circuit for detecting a momentary voltage drop caused by a lightning strike on a power transmission line (not shown), etc. As shown in Fig. 1, the momentary power interruption detection circuit 40 is mounted on a control board B4. In addition, a predetermined microcomputer and a control circuit may be mounted on the control board B4.

[0014] The electric box X1 shown in Fig. 1 is a box for accommodating a terminal block B1, a noise filter board B2, an inverter board B3, and a control board B4. The 200V load 50 is, for example, a load such as an expansion valve or a four-way valve of an air conditioner. A single-phase AC voltage is supplied to the 200V load 50 via the noise filter board B2. Note that "200V" is just an example, and the rated voltage of the load may be a value other than 200V.

[0015] FIG. 2 is a circuit diagram showing the configuration of the electric circuit body 100. As shown in FIG. As described above, a three-phase, four-wire AC power source E1 is used to distribute power to the electric circuit body 100. Specifically, the R-phase power line 8 R and S-phase power line 8 S and T-phase power line 8 T and N-phase neutral wire 8 N and are connected via a terminal block B1 to a noise filter circuit 10. The noise filter circuit 10 is a circuit for suppressing disturbance surges and lightning surges, and is connected to a three-phase four-wire AC power source E1 via the terminal block B1.

[0016] As shown in FIG. 2, the noise filter circuit 10 includes a first varistor 1 R ,1 S ,1 T (First surge protection element) and discharge resistor 2 R ,2 S ,2T and the 1st capacitor 3 R ,3 S ,3 T (X capacitor) and Y capacitor 4 R ,4 S ,4 T and the second capacitor 5 R ,5 S ,5 T In addition to the above-mentioned configuration, the noise filter circuit 10 further includes a second varistor 6. N (second surge protection element) and a surge absorber 7.

[0017] R-phase power line 8 R The first varistor connected to R The first varistor 1 is a resistive element whose voltage-current characteristics are non-linear. R The first varistor 1 has a characteristic that its resistance value decreases rapidly when the voltage applied to it exceeds a predetermined value. R When a high voltage is momentarily applied to the first varistor 1 R The resistance of the first varistor 1 drops sharply. R This protects the inverter circuit 20 at the rear stage of the noise filter circuit 10 from disturbance surges and the like. S The first varistor connected to S , T-phase power line 8 T The first varistor connected to T The same applies to.

[0018] As shown in FIG. 2, each of the first varistors 1 R ,1 S ,1 T (First surge protection element) One end of the element is connected to the three-phase power line 8. R ,8 S ,8 T For example, the first varistor 1 of the R phase is R One end of the lead wire (one of the pair of lead wires) is connected to the R-phase power line 8 via wiring. RSimilarly, the first varistor of S phase 1 S One end of the S-phase power line 8 S and the first varistor of T phase 1 T One end of the T-phase power line 8 T is connected to

[0019] In addition, each of the first varistors R ,1 S ,1 T The other ends of the first surge protection elements are connected to each other. R The other end of the lead wire (the other of the pair of lead wires) and the first varistor 1 of the S phase S The other end of the first varistor of the T phase T The other end of and are connected to each other.

[0020] As shown in Figure 2, the neutral wire of N phase 8 N The first varistor R ,1 S ,1 T In other words, each of the first varistors 1 R ,1 S ,1 T The other end of the (first surge protection element) is the neutral conductor 8 N The neutral conductor is not connected to the N "Not connected" means that the first varistor R ,1 S ,1 T The other end of the wire is connected to the neutral wire 8 via wiring. N This means that the first varistor 1 is not directly connected to the R ,1 S ,1 T Neutral conductor 8 N By configuring it so that it is not connected to the first varistor 1 when the N phase is lost, R ,1 S ,1 T As a result, when the N-phase is lost, the first varistor 1 R ,1 S ,1 TThis can prevent damage or malfunction of the device.

[0021] Discharge resistor 2 R 1st capacitor x 3 R It is a resistor element for dissipating the residual charge of the R phase. One end of the resistor is connected to the R phase power line 8 via wiring. R Similarly, the discharge resistor 2 of the S phase is connected to S One end of the S-phase power line 8 S Also, the discharge resistor 2 of the T phase is connected to T One end of the T-phase power line 8 T That is, the discharge resistor 2 R ,2 S ,2 T One end of the 3-phase power line R ,8 S ,8 T In addition, the discharge resistor 2 R ,2 S ,2 T The other end of each of the first varistors 1 R ,1 S ,1 T and the other end of each of the inputs are connected to each other.

[0022] 1stX Capacitor 3 R is a capacitor that is mainly used to suppress normal mode noise, and one end of the capacitor is connected to the R-phase power line 8 via a wiring. R Similarly, the first X capacitor of the S phase is connected to S One end of the S-phase power line 8 S and the first X capacitor 3 of the T phase is connected to T One end of the T-phase power line 8 T That is, the first X capacitor 3 R ,3 S ,3 T One end of the 3-phase power line R ,8 S ,8 T are individually connected to each other.

[0023] Also, the first capacitor 3 R ,3 S ,3T The other end of each of the first varistors 1 R ,1 S ,1 T and discharge resistor 2 R ,2 S ,2 T In other words, the first varistor 1 R ,1 S ,1 T (First surge protection element), Discharge resistor 2 R ,2 S ,2 T , and 1X capacitor 3 R ,3 S ,3 T The other ends of each of the (X capacitors) are connected to each other.

[0024] In addition, the first varistor R ,1 S ,1 T and discharge resistor 2 R ,2 S ,2 T 1st capacitor x 3 R ,3 S ,3 T The other ends of the resistors are connected to each other, but the connection does not need to be grounded. If the connection is grounded, the discharge resistor 2 R ,2 S ,2 T This is because leakage current is likely to flow through the leakage current supply, which may result in an increased possibility of a leakage current breaker (not shown) tripping during normal operation.

[0025] Y Capacitor 4 R is a capacitor that is mainly used to suppress common mode noise, and one end of the capacitor is connected to the R-phase power line 8 via a wiring. R Similarly, the Y capacitor 4 of the S phase is connected to S One end of the S-phase power line 8 S Also, the Y capacitor 4 of the T phase is connected to T One end of the T-phase power line 8 T That is, the Y capacitor is connected to R ,4 S ,4 TOne end of the 3-phase power line R ,8 S ,8 T In addition, the Y capacitor 4 R ,4 S ,4 T The other end of each is a neutral conductor 8 N (More specifically, the third neutral conductor 83 N ) is grounded.

[0026] 2nd Capacitor 5 R is a capacitor that is mainly used to suppress normal mode noise, and one end of the capacitor is connected to the R-phase power line 8 via a wiring. R Similarly, the second X capacitor 5 of the S phase is connected to S One end of the S-phase power line 8 S and the second X capacitor 5 of the T phase is connected to T One end of the T-phase power line 8 T Also, the second X capacitor 5 R ,5 S ,5 T The other ends of the first X capacitor 3 are connected to each other. R ,3 S ,3 T and Y capacitor 4 R ,4 S ,4 T And 2nd Capacitor 5 R ,5 S ,5 T The inclusion of this in the noise filter circuit 10 improves the attenuation characteristics when attenuating noise.

[0027] Neutral conductor 8 shown in Figure 2 N 1st neutral conductor 81 N and the second neutral conductor 82 N and the third neutral conductor 83 N The first neutral conductor 81 N One end of the resistor is connected to the terminal block B1, and the other end is connected to the second varistor 6 N The second neutral conductor 82 is grounded through the surge absorber 7 in this order. N One end of the first neutral conductor 81 N(Terminal block B1 and second varistor 6 N The other end is branched into three and connected to the power supply circuit 30, the momentary power interruption detection circuit 40, and the 200V load 50. N One end of the Y capacitor 4 R ,4 S ,4 T The other end is connected to the connection point of the first neutral conductor 81. N (the ground side of the surge absorber 7).

[0028] 2nd Barista 6 N The second surge protection element is an element for suppressing instantaneous voltage fluctuations (surges), and is connected to the first neutral conductor 81. N As described above, since the noise filter circuit 10 is mounted on the noise filter board B2 (see FIG. 1), the second varistor 6 N (The second surge protection element) is also mounted on the noise filter board B2 (see FIG. 1) together with other elements.

[0029] The surge absorber 7 is an element that absorbs a surge (by reducing the resistance value to allow a current to flow) when a disturbance surge or a lightning surge occurs and a high voltage is applied. N In the example of FIG. 2, one end of the surge absorber 7 is connected to the second varistor 6. N and the other end is grounded.

[0030] The inverter circuit 20 is connected to the noise filter circuit 10 via the power line 8 R ,8 S ,8 T The inverter circuit 20 is a power converter that converts a three-phase AC voltage applied via the neutral line 8 into a DC voltage, and further converts the DC voltage into a predetermined three-phase AC voltage and applies it to the three-phase windings of the motor M1. N 8 Different three-phase power lines R ,8 S ,8 T 1. The input terminal of the noise filter circuit 10 is connected to the output terminal of the noise filter circuit 10 via the

[0031] 2, the inverter circuit 20 includes a rectifier circuit 21, a reactor 22, a smoothing capacitor 23, an inverter 24, a microcomputer 25, and a control circuit 26. The rectifier circuit 21 rectifies a three-phase AC voltage of R, S, and T phases applied via the noise filter circuit 10, and converts it into a pulsating DC voltage. For example, a diode bridge circuit is used as the rectifier circuit 21. The output side of the rectifier circuit 21 is connected to the inverter 24 via a positive wiring 27a and is also connected to the inverter 24 via a negative wiring 27b.

[0032] The reactor 22 has a function of suppressing harmonics, and is provided on the positive side wiring 27a. The smoothing capacitor 23 smoothes the pulsating DC voltage applied from the rectifier circuit 21. The positive electrode of the smoothing capacitor 23 is connected to the positive side wiring 27a (between the reactor 22 and the inverter 24), and the negative electrode is connected to the wiring 27b.

[0033] The inverter 24 is a circuit that converts the DC voltage smoothed by the smoothing capacitor 23 into a predetermined three-phase AC voltage. The inverter 24 is configured with a first leg, a second leg, and a third leg, each equipped with a pair of switching elements S1, S2, connected in parallel to one another. The positive sides of the first leg, the second leg, and the third leg are connected to a wiring 27a, and the negative sides are connected to a wiring 27b. In addition, the connection points of the pairs of switching elements S1 and S2 of each leg are connected to the three-phase windings of the motor M1 via wiring, respectively.

[0034] The microcomputer 25 calculates a voltage command value and a current command value for the motor M1 based on a predetermined program. The control circuit 26 executes PWM control (Pulse Width Modulation) based on a command signal from the microcomputer 25, and outputs a predetermined PWM signal to the inverter 24. This causes each of the switching elements S1 and S2 to be switched on and off in a predetermined manner.

[0035] As described above, the power supply circuit 30 shown in FIG. 2 is a circuit that generates predetermined DC voltages (DC voltages Vdd1, Vdd2, and Vdd3). The power supply circuit 30 includes three-phase power lines 8. R ,8 S ,8 T One of the power lines (in the example of Figure 2, the R-phase power line 81 R ) and neutral conductor 8 N A single-phase AC voltage is applied through the R-phase power line 81. R One end of the cable is connected to a power line R The other end is branched into three and connected to the input side of the power supply circuit 30, the momentary power interruption detection circuit 40, and the 200V load 50.

[0036] 2, the power supply circuit 30 includes a third varistor 31, a filter circuit 32, an NTC (Negative Temperature Coefficient) thermistor 33, a rectifier circuit 34, a smoothing capacitor 35, and a DC / DC converter 36. The third varistor 31 has a function of suppressing disturbance surges and lightning surges on the input side of the power supply circuit 30. The filter circuit 32 is a circuit for suppressing harmonics accompanying the operation of the power supply circuit 30.

[0037] The NTC thermistor 33 is an element whose resistance value changes with temperature change, and functions as an inrush current prevention resistor. As shown in Fig. 2, the NTC thermistor 33 is provided on one side (wire 37a in the example of Fig. 2) of a pair of wires 37a, 37b that connect the filter circuit 32 and the rectifier circuit 34. The rectifier circuit 34 converts the single-phase AC voltage applied via the filter circuit 32 into a pulsating DC voltage.

[0038] The smoothing capacitor 35 is a capacitor that smoothes the pulsating DC voltage applied from the rectifier circuit 34. The DC / DC converter 36 is a circuit that converts the DC voltage smoothed by the smoothing capacitor 35 into a DC voltage of a predetermined level. Of the DC voltages converted by the DC / DC converter 36, a predetermined DC voltage Vdd1 is applied to the microcomputer 25 of the inverter circuit 20, and another DC voltage Vdd2 is applied to the microcomputer 44 of the instantaneous power failure detection circuit 40. In addition, the DC voltage Vdd3 is applied to the control circuit 26 of the inverter circuit 20.

[0039] As described above, the instantaneous power interruption detection circuit 40 is a circuit for detecting an instantaneous voltage drop caused by a lightning strike on a power transmission line (not shown), etc. As shown in Fig. 2, the instantaneous power interruption detection circuit 40 includes a filter circuit 41, voltage dividing resistors 42a and 42b, an insulation circuit 43, and a microcomputer 44. The filter circuit 41 is a circuit for suppressing harmonics.

[0040] The voltage dividing resistors 42a and 42b are resistive elements for dividing the voltage on the output side of the filter circuit 41 to a predetermined value. In the example of Fig. 2, the voltage dividing resistor 42a is provided on one wiring 45a of a pair of wirings 45a and 54b on the output side of the filter circuit 41. The other voltage dividing resistor 42b has one end connected to the wiring 45a and the other end connected to the wiring 45b.

[0041] The insulating circuit 43 outputs a predetermined signal to the microcomputer 44, the value of which is proportional to the voltage across the voltage dividing resistor 42b, while electrically insulating the microcomputer 44. For example, a photocoupler is used as the insulating circuit 43. When the microcomputer 44 determines that an instantaneous power interruption has occurred based on the signal input from the insulating circuit 43, it outputs a predetermined signal indicating the instantaneous power interruption to the microcomputer 25 of the inverter circuit 20. This causes the inverter circuit 20 to stop when an instantaneous power interruption has occurred. Next, the configuration of a comparative example (see FIG. 8) will be described, and then the operation and effect of the electric circuit body 100 of the first embodiment will be described.

[0042] FIG. 8 is a circuit diagram showing the configuration of an electric circuit body 100G according to a comparative example. In addition, in the comparative example of FIG. 8, the neutral wire 8 of the N phase N (Specifically, the first neutral conductor 81 N ) is the first varistor 1 R ,1 S ,1 T The first embodiment differs from the first embodiment (see FIG. 2) in that the first X capacitor 3 is connected to the other end of the first X capacitor 3. R ,3 S ,3 T and Y capacitor 4 R ,4 S ,4 T The other end of each of the second varistors 6 N and a surge absorber 7 in sequence. The remaining features are the same as those of the first embodiment, and therefore will not be described.

[0043] In the configuration shown in FIG. 8, during normal operation when no missing phase occurs in the N phase, the first varistor 1 R ,1 S ,1 T In other words, a phase voltage of 1 / √3 of the line voltage of the AC power supply E1 is applied to the first varistor 1. R ,1 S ,1 T is applied to each of the

[0044] However, when installing the electric circuit body 100, the worker may N Forgot to connect the neutral wire or N Poor connection of the neutral wire or N In the case where the neutral conductor 8 of the electric circuit body 100 is broken, a loss of N phase may occur. N This means that the power supply E1 is no longer electrically connected to the AC power supply E1.

[0045] In the configuration of the comparative example of FIG. 8, when the N phase is lost, the first varistor 1 R ,1 S ,1 TIn other words, a line voltage that is √3 times the phase voltage that is normally applied is applied to the first varistor 1. R ,1 S ,1 T This line voltage is applied to the first varistor 1 R ,1 S ,1 T If the withstand voltage of the first varistor is higher than that of the R ,1 S ,1 T may be damaged by overvoltage.

[0046] In contrast, in the first embodiment (see FIG. 2), the N-phase neutral wire 8 N The first varistor is R ,1 S ,1 T The R, S, and T phase power lines are not connected to the R ,8 S ,8 T As a result, even if an N-phase loss occurs, there is no current path for the line voltage, so the first varistor 1 R ,1 S ,1 T That is, in a configuration in which power is supplied from a three-phase four-wire AC power source E1, even if the Nth phase is lost, the first varistor 1 R ,1 S ,1 T Therefore, the reliability is improved compared to the comparative example.

[0047] Also, the first varistor R ,1 S ,1 T Since the other ends of the varistors are connected to each other, regardless of whether there is an open phase or not, a phase voltage of 1 / √3 of the line voltage is applied to the first varistor R ,1 S ,1 T As a result, the first varistor 1 R ,1 S ,1 T Since a material having a low withstand voltage can be used as the resistor, the manufacturing cost of the electric circuit body 100 can be reduced.

[0048] Also, the first neutral conductor 81 N 2nd varistor 6 N Since a surge absorber 7 is provided, the first neutral conductor 81 N The second varistor 6 can suppress external surges between the inverter and the earth (ground point). N Since the surge absorber 7 is mounted on the noise filter board B2 (see FIG. 1), the first neutral conductor 81 N and the earth (ground point), the noise filter substrate B2 can appropriately suppress disturbance surges.

[0049] Second Embodiment In the second embodiment, the first varistor 1 R ,1 S ,1 T (See Figure 3) are not connected to each other, and the other ends of the power lines 8 R ,8 S ,8 T (see FIG. 3) in a one-to-one relationship. The rest is the same as in the first embodiment. Therefore, only the parts that are different from the first embodiment will be described, and a description of the overlapping parts will be omitted.

[0050] FIG. 3 is a circuit diagram showing the configuration of an electric circuit body 100A according to the second embodiment. As shown in FIG. 3, the noise filter circuit 10A of the electric circuit body 100A includes a first varistor 1 R ,1 S ,1 T Each of the first varistors 1 is provided with various elements such as a first surge protection element. R ,1 S ,1 T One end of the 3-phase power line R ,8 S ,8 T The first varistor 1 R ,1 S ,1 T The other end is the neutral conductor 8 N These points are the same as those in the first embodiment (see FIG. 2).

[0051] In addition, each of the first varistors R ,1 S ,1 T The other ends of the first varistor 1 are not connected to each other. R ,1 S ,1 T The first varistor 1 is connected to a power line different from the one connected to the other end of the first varistor 1. R One end of the R-phase power line 8 R and the other end is connected to the S-phase power line 8 S Another first varistor 1 S One end of the power line is S-phase 8. S and the other end is connected to the T-phase power line 8 T The remaining first varistor 1 T One end of the power line is the T-phase 8 T and the other end is connected to the R-phase power line 8. R In this way, each of the first varistors 1 R ,1 S ,1 T (First surge protection element) is a first varistor 1 R ,1 S ,1 T The other end of the power line is connected to the three-phase power line 8 so that the R ,8 S ,8 T is connected to one of the

[0052] Discharge resistor 2 R ,2 S ,2 T One end of the 3-phase power line R ,8 S ,8 T Similarly, the first X capacitor 3 R ,3 S ,3 T (X capacitor) has one end connected to the three-phase power line 8 R ,8 S ,8 T In addition, the discharge resistor 2 R ,2 S ,2T and 1X capacitor 3 R ,3 S ,3 T The other ends of the respective ones are connected to each other.

[0053] For example, in normal operation when no missing phase occurs in the N phase, the first varistor 1 R ,1 S ,1 T The line voltage of the AC power supply E1 is applied to each of the first varistor 1 and the second varistor 2. R ,1 S ,1 T The line voltage of the AC power supply E1 is applied to each of the first varistors 1 and 2. R ,1 S ,1 T Therefore, the voltage applied to the first varistor 1 hardly changes. R ,1 S ,1 T By using a varistor whose withstand voltage is higher than the line voltage of the AC power supply E1, the first varistor 1 R ,1 S ,1 T This can prevent damage or malfunction.

[0054] Also, if the discharge resistor is 2 R ,2 S ,2 T 1st capacitor x 3 R ,3 S ,3 T Even if the first varistor 1 is short-circuited and a short circuit occurs, the first varistor 1 R ,1 S ,1 T The line voltage of the AC power supply E1 is applied to each of the first varistor 1. R ,1 S ,1 T This can prevent damage or malfunction of the device and improve reliability.

[0055] Third Embodiment In the third embodiment, an air conditioner 200 (see FIG. 4) including an electric circuit body 100 (see FIG. 2) will be described. Note that the configuration of the electric circuit body 100 (see FIG. 2) is similar to that of the first embodiment, and therefore description thereof will be omitted.

[0056] FIG. 4 is a configuration diagram of an air conditioner 200 according to the third embodiment. The solid arrows in FIG. 4 indicate the flow of the refrigerant in the heating cycle. Moreover, the dashed arrows in FIG. 4 indicate the flow of the refrigerant in the cooling cycle. The air conditioner 200 is a device that performs air conditioning such as cooling operation and heating operation, and includes an outdoor unit U1 and an indoor unit U2. The outdoor unit U1 and the indoor unit U2 are connected via a refrigerant pipe.

[0057] The air conditioner 200 includes, as components provided in the outdoor unit U1, a compressor 61, an outdoor heat exchanger 62, an outdoor fan 63, an expansion valve 64, and a four-way valve 67. The air conditioner 200 also includes, as components provided in the indoor unit U2, an indoor heat exchanger 65 and an indoor fan 66.

[0058] The compressor 61 is a device that compresses a low-temperature, low-pressure gas refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant, and is equipped with a compressor motor 61a that serves as a drive source. Note that the motor M1 (see FIG. 2) on the load side of the electric circuit body 100 (see FIG. 2) may be the compressor motor 61a or an outdoor fan motor 63a, which will be described later. In addition, although not shown in FIG. 4, an accumulator 68 (see FIG. 5) for separating the refrigerant into gas and liquid is provided on the suction side of the compressor 61.

[0059] The outdoor heat exchanger 62 is a heat exchanger in which heat exchange takes place between a refrigerant flowing through its heat transfer tubes 62b (see FIG. 5) and outside air sent from an outdoor fan 63. The outdoor fan 63 is a fan that sends outside air to the outdoor heat exchanger 62. The outdoor fan 63 is provided with an outdoor fan motor 63a that serves as a drive source, and is installed near the outdoor heat exchanger 62.

[0060] The expansion valve 64 is a valve that reduces the pressure of the refrigerant condensed in the "condenser" (one of the outdoor heat exchanger 62 and the indoor heat exchanger 65). The refrigerant reduced in pressure by the expansion valve 64 is guided to the "evaporator" (the other of the outdoor heat exchanger 62 and the indoor heat exchanger 65). The indoor heat exchanger 65 is a heat exchanger in which heat exchange takes place between the refrigerant flowing through its heat transfer tube (not shown) and indoor air (air in the air-conditioned room) sent from the indoor fan 66. The indoor fan 66 is a fan that sends indoor air to the indoor heat exchanger 65, and is installed near the indoor heat exchanger 65.

[0061] The four-way valve 67 is a valve that switches the flow path of the refrigerant depending on the operation mode of the air conditioner 200. For example, in a cooling cycle (see the dashed arrow in FIG. 4), the refrigerant circulates in the refrigerant circuit Q1 sequentially through the compressor 61, the outdoor heat exchanger 62 (condenser), the expansion valve 64, and the indoor heat exchanger 65 (evaporator). Also, in a heating cycle (see the solid arrow in FIG. 4), the refrigerant circulates in the refrigerant circuit Q1 sequentially through the compressor 61, the indoor heat exchanger 65 (condenser), the expansion valve 64, and the outdoor heat exchanger 62 (evaporator).

[0062] When the air conditioner 200 receives power from a three-phase, four-wire AC power source E1 (see FIG. 2), power can be supplied to the outdoor unit U1 either via the indoor unit U2 or without passing through the indoor unit U2.

[0063] FIG. 5 is a perspective view of the outdoor unit U1 with the side and top panels removed from the housing 69. FIG. As shown in FIG. 5, in a housing 69 of the outdoor unit U1, in addition to the compressor 61, the accumulator 68, the outdoor heat exchanger 62, and the outdoor fan 63, an electric box X1 is installed.

[0064] An outdoor heat exchanger 62 having an L-shape in plan view is installed on a bottom plate 69a of the housing 69. The outdoor heat exchanger 62 includes a number of fins 62a arranged at predetermined intervals and a number of heat transfer tubes 62b penetrating the fins 62a. Heat exchange is performed between the outside air sent by the outdoor fan 63 and the refrigerant flowing through the heat transfer tubes 62b. The electric box X1 shown in FIG. 5 is a metal box that houses the electric circuit body 100 (see FIG. 2) and is electrically grounded. In this manner, the electric circuit body 100 (see FIG. 2) is installed in the outdoor unit U1.

[0065] According to the third embodiment, since the outdoor unit U1 of the air conditioner 200 includes the electric circuit body 100 (see FIG. 2), even if an N-phase loss occurs in a configuration receiving a three-phase four-wire power supply, the first varistor 1 R ,1 S ,1 T (See FIG. 2) can be prevented from being damaged or malfunctioning. Therefore, the reliability of the air conditioner 200 can be improved more than ever before.

[0066] <<Variations>> Although the electric circuit body 100, 100A (see Figs. 2 and 3) and the air conditioner 200 (see Fig. 4) according to the present disclosure have been described in each embodiment above, the present disclosure is not limited to these descriptions and may be modified in various ways. For example, in the first embodiment, the second varistor 6 N In the above description, a configuration has been described in which the noise filter circuit 10 (i.e., the noise filter board B2: see FIG. 1) is provided with a surge absorber 7 (see FIG. 2) and a noise filter board B3 (see FIG. 2). However, the present invention is not limited to this configuration, and may be configured as shown in FIG. 6.

[0067] FIG. 6 is a circuit diagram showing the configuration of an electric circuit body 100B according to a first modified example. In addition, the configuration of FIG. 6 includes the second varistor 6 N The second surge protection element (second surge protection element) and the surge absorber 7 are not included in the noise filter circuit 10B, but are included in the power supply circuit 30B instead, which is different from the first embodiment (see FIG. 2).N The surge absorber 7 is mounted on the inverter board B3 (see FIG. 1). Even with this configuration, the same effects as those of the first embodiment can be achieved. N By providing the above, the noise suppression effect in the power supply circuit 30 is improved.

[0068] FIG. 7 is a circuit diagram showing the configuration of an electric circuit body 100C according to a second modified example. The configuration in Fig. 7 differs from the first embodiment (see Fig. 2) in that a fourth varistor 71 and a surge absorber 72 are added to the noise filter circuit 10C. The fourth varistor 71 and the surge absorber 72 have the function of suppressing a lightning surge when the surge occurs between the R phase and earth (ground point), between the S phase and earth, or between the T phase and earth. Specifically, one end of the fourth varistor 71 is connected to the first varistor 1. R ,1 S ,1 T and discharge resistor 2 R ,2 S ,2 T 1st capacitor x 3 R ,3 S ,3 T The other end of the fourth varistor 71 is connected to the surge absorber 72 and the third neutral wire 83. N According to this configuration, even if a lightning surge occurs between the R phase, the S phase, or the T phase and the earth, the lightning surge is suppressed by the fourth varistor 71 and the surge absorber 72, thereby improving the reliability of the electric circuit body 100C. In addition, during normal times when no lightning surge is occurring, the resistance value of the fourth varistor 71, etc. is considerably large, so no current flows through the fourth varistor 71, etc. In other words, during normal times, the first varistor 1 R ,1 S ,1 T (First surge protection element) and the other end of the neutral wire 8 N Therefore, even in the configuration of FIG. 7, the first varistor 1 R ,1 S ,1 TThis can prevent an overvoltage from being applied to the

[0069] Although the embodiments do not particularly mention a common mode coil (not shown), the noise filter circuit 10 (see FIG. 2) may include a common mode coil. R ,8 S ,8 T In the Y capacitor 4 R ,4 S ,4 T A common mode coil may be provided on one or both sides of the coil, which further enhances the effect of suppressing common mode noise.

[0070] In each embodiment, the first varistor 1 is used as the "first surge protection element." R ,1 S ,1 T In the above description, the second varistor 6 is used, but the present invention is not limited to this. That is, a Zener diode (TVS; Transient Voltage Suppressor) or an avalanche diode may be used as the "first surge protection element." N The same applies to the third varistor 31.

[0071] In each embodiment, the noise filter circuit 10 (see FIG. 2) includes a second varistor 6 N The configuration including the second varistor 6 and the surge absorber 7 has been described. N It is also possible to omit one of the surge absorbers 7 as appropriate. In each embodiment, the noise filter circuit 10 (see FIG. 2) includes a first X capacitor 3 R ,3 S ,3 T and Y capacitor 4 R ,4 S ,4 T And 2nd Capacitor 5 R ,5 S ,5 T However, some of these may be omitted as appropriate.

[0072] In each embodiment, the noise filter circuit 10 (see FIG. 2) includes three first varistors 1 R ,1 S ,1 T In the above description, the noise filter circuit 10 includes a first varistor (first surge protection element), but the present invention is not limited to this. That is, the number of first varistors may be four or more. In other words, the noise filter circuit 10 may include at least three first varistors (first surge protection elements). As a specific example, one end of a plurality of first varistors connected in series or parallel may be connected to the R-phase power line 8. R The same can be said for the other first varistors corresponding to the S phase and the T phase.

[0073] In the first embodiment, the first varistor 1 R ,1 S ,1 T (See Figure 2) and the other end of discharge resistor 2 R ,2 S ,2 T (See Figure 2) and 1st X capacitor 3 R ,3 S ,3 T In the above description, the other end of the first varistor 1 (see FIG. 2) is connected to the other end of the first varistor 1. However, the present invention is not limited to this. R ,1 S ,1 T (See Figure 2) and the other end of discharge resistor 2 R ,2 S ,2 T (See Figure 2) and 1st X capacitor 3 R ,3 S ,3 T Even in a configuration in which the other ends of the first and second electrodes (see FIG. 2) are not connected to each other, the same effects as in the first embodiment can be achieved.

[0074] In the third embodiment, the electric circuit body 100 (see FIG. 2) is installed in the outdoor unit U1 (see FIG. 4), but the present invention is not limited to this. For example, the electric circuit body 100 may be installed in the indoor unit U2 (see FIG. 4), or may be installed in both the outdoor unit U1 and the indoor unit U2. In other words, the electric circuit body 100 may be installed in at least one of the outdoor unit U1 and the indoor unit U2.

[0075] In addition, the embodiments can be combined as appropriate. For example, the electric circuit body 100A (see FIG. 3) described in the second embodiment may be installed in the outdoor unit U1 (see FIG. 4) of the air conditioner 200 described in the third embodiment.

[0076] Furthermore, in the third embodiment, a configuration in which the air conditioner 200 (see FIG. 4) includes the four-way valve 67 (see FIG. 4) has been described, but the present invention is not limited to this. That is, the four-way valve 67 may be omitted from the air conditioner 200, and the air conditioner may be configured to be dedicated to cooling or heating. In the third embodiment, a configuration in which one outdoor unit U1 (see FIG. 4) and one indoor unit U2 (see FIG. 4) are provided has been described, but the present invention is not limited to this. That is, a plurality of indoor units connected in parallel may be provided, and a plurality of outdoor units connected in parallel may be provided.

[0077] Furthermore, in the third embodiment, a case has been described in which the air conditioner 200 (see FIG. 4) is a room air conditioner, but the third embodiment can also be applied to various types of air conditioners, such as commercial air conditioners and multi-air conditioners for buildings. In the third embodiment, the case where the device receiving AC power in a three-phase, four-wire system is the air conditioner 200 (see FIG. 4) has been described, but the present invention is not limited to this. That is, each embodiment can be applied to various devices such as water heaters, refrigerators, and washing machines, so long as the device receives AC power in a three-phase, four-wire system.

[0078] In addition, each embodiment has been described in detail to clearly explain the present disclosure, and is not necessarily limited to having all of the configurations described. In addition, it is possible to add, delete, or replace part of the configuration of an embodiment with other configurations. Furthermore, the above-mentioned mechanisms and configurations are those considered necessary for the explanation, and do not necessarily show all mechanisms and configurations of the product. [Explanation of symbols]

[0079] 1 R ,1 S ,1 T First varistor (first surge protection element) 2 R ,2 S ,2 T Discharge Resistor 3 R ,3 S ,3 T 1st X capacitor (X capacitor), 4 R ,4 S ,4 T Y Capacitor 5 R ,5 S ,5 T 2nd X Capacitor 6 N Second varistor (second surge protection element) 7 Surge absorber 8 R ,81 R ,8 S ,8 T Power lines 8 N Neutral conductor 10, 10A, 10B, 10C Noise filter circuit 20 Inverter circuit 30,30B power supply circuit 40 Instantaneous power failure detection circuit 50 200V load 71 4th Barista 72 Surge absorber 81 N No. 1 Neutral Wire 82 N Second Neutral Wire 83 N 3rd Neutral Wire 100, 100A, 100B, 100C Electric circuit body 200 Air conditioner B1 terminal block B2 Noise filter board B3 Inverter Board B4 Control Board E1 AC power supply M1 Motor Q1 Refrigerant circuit U1 outdoor unit U2 indoor unit X1 Electric box

Claims

1. a noise filter circuit connected to a three-phase four-wire AC power supply; an inverter circuit connected to an output side of the noise filter circuit via a three-phase power line different from a neutral line; a power supply circuit to which a single-phase AC voltage is applied via one of the three-phase power lines and the neutral line; the noise filter circuit has at least three first surge protection elements; An electric circuit body, wherein one end of each of the first surge protection elements is connected to one of the three-phase power lines and the other end is not connected to the neutral line.

2. The other ends of the first surge protection elements are connected to each other.

2. The electrical circuit assembly according to claim 1 .

3. The neutral conductor is a first neutral conductor having one end connected to the terminal block and the other end grounded; a second neutral conductor having one end connected to the first neutral conductor and the other end connected to the power supply circuit; A second surge protection element is provided on the first neutral conductor.

2. The electrical circuit assembly according to claim 1 .

4. a noise filter substrate on which the noise filter circuit is mounted, The second surge protection element is mounted on the noise filter substrate.

4. The electric circuit assembly according to claim 3.

5. an inverter board on which the inverter circuit and the power supply circuit are mounted, The second surge protection element is mounted on the inverter board.

4. The electric circuit assembly according to claim 3.

6. The other end of each of the first surge protection elements is connected to one of the three-phase power lines so that a line voltage of the AC power supply is applied to the first surge protection element, The noise filter circuit includes: Discharge resistors each having one end connected to one of the three-phase power lines; An X capacitor having one end connected to each of the three phases of the power lines, The other end of the discharge resistor and the other end of the X capacitor are connected to each other.

2. The electrical circuit assembly according to claim 1 .

7. A heat exchanger comprising the electric circuit body according to any one of claims 1 to 6, an outdoor unit, and an indoor unit connected to the outdoor unit via a refrigerant pipe, The electric circuit body is installed in at least one of the outdoor unit and the indoor unit.

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